When is the parallel combination of cells advantageous and why?

Explanation

### Step-by-Step Solution:

1. **Understanding Internal and External Resistance**:
- Cells have an internal resistance (r) which affects their performance when connected to an external circuit that has its own resistance (R).
- The internal resistance of the cell is the resistance to the flow of current within the cell itself, while the external resistance is the resistance of the circuit connected to the cell.

2. **Condition for Parallel Combination**:
- A parallel combination of cells is advantageous when the internal resistance of the cells is significantly greater than the external resistance. This means \( r \gg R \).
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